Many people hear the terms “insulin resistance” and “prediabetes” used as if they mean the same thing. While the two are closely connected, they represent different stages of a process that can ultimately lead to type 2 diabetes.
Insulin resistance is the body’s earliest warning sign that cells aren’t responding properly to insulin, while prediabetes indicates that blood sugar levels are already creeping above normal.
The two can have different warning signs and understanding them can lead to better prevention, early treatment and improved long-term health.
What Is Insulin Resistance?
Insulin resistance happens when the body’s cells don’t respond properly to insulin, a hormone made by the pancreas that helps move glucose (sugar) from the bloodstream into cells for energy.
In response, the pancreas produces more insulin to compensate. For a while, this can keep blood sugar levels normal. But over time, the pancreas can’t keep up and blood sugar levels begin to rise.
Insulin resistance often develops silently, with no clear symptoms. It can go undetected for years in some cases.
What Causes Insulin Resistance?
Common causes and risk factors for insulin resistance include:
- Being overweight or obese (which has a strong link to type 2 diabetes), especially with excess abdominal fat (called visceral fat)
- Living a sedentary lifestyle
- Family history of type 2 diabetes
- Hormonal conditions such as polycystic ovary syndrome (PCOS) or Cushing’s syndrome
- Chronic stress and poor sleep
- Taking certain medications, such as glucocorticoids and antipsychotics
- Being over 35
- Smoking
What Is Prediabetes?
Prediabetes occurs when blood sugar levels are higher than normal, but not yet high enough for a diagnosis of type 2 diabetes. This condition is considered a warning stage that shows the body is no longer able to regulate blood sugar effectively.
According to the CDC, over 96 million (1 in 3) U.S. adults have prediabetes and the vast majority (about 80 percent) don’t know it because there aren’t always noticeable symptoms.
How is Prediabetes Diagnosed?
The three tests below, which are diagnostic thresholds for prediabetes, are different ways to measure blood sugar, according to the American Diabetes Association:
Fasting Blood Glucose (100–125 mg/dL):
This test measures your blood sugar after not eating (fasting) for at least 8 hours. Think of it as a “morning check” of how well your body controls blood sugar without food.
- Normal: below 100 mg/dL
- Prediabetes: 100–125 mg/dL → your body isn’t handling sugar as well as it should
- Diabetes: 126 mg/dL or higher (on two separate tests)
Hemoglobin A1C (5.7 percent to 6.4 percent):
This blood test shows your average blood sugar over the past 2-3 months. It’s like a “long-term report card” for your blood sugar.
- Normal: below 5.7 percent
- Prediabetes: 5.7 percent to 6.4 percent
- Diabetes: 6.5 percent or higher
Oral Glucose Tolerance Test (OGTT: 140–199 mg/dL after 2 hours):
For this test, you drink a sweet liquid and your blood sugar is checked 2 hours later. This test shows how well your body handles a sugar load. If your sugar stays too high after 2 hours, it means your insulin isn’t working properly.
- Normal: below 140 mg/dL
- Prediabetes: 140–199 mg/dL
- Diabetes: 200 mg/dL or higher
What Causes Prediabetes?
Prediabetes often develops from long-standing insulin resistance. In other words, insulin resistance is a precursor to prediabetes.
Having prediabetes can also significantly raise the risk of developing type 2 diabetes, as well as heart disease, stroke, kidney failure, blindness and other conditions. That’s because elevated blood sugar damages blood vessels and can accelerate atherosclerosis (plaque buildup in the arteries).
Key Differences Between Insulin Resistance and Prediabetes
Insulin resistance comes before prediabetes.
After someone is insulin resistant, prediabetes is the next stage when blood sugar levels have already started to climb.
Insulin resistance is also usually harder to detect without specialized testing. Prediabetes can be diagnosed through routine blood tests, including those described above.
Not everyone with insulin resistance will develop prediabetes. But almost everyone with prediabetes has some degree of insulin resistance.
Symptoms to Watch For
Both insulin resistance and prediabetes often develop without obvious symptoms, but certain signs may signal a concern and should be discussed with your healthcare provider:
Signs of insulin resistance:
- Fatigue after meals
- Cravings for carbs or sweets
- Difficulty losing weight, especially around the waist
- Darkened patches of skin (called acanthosis nigricans), especially on the neck or armpits
Signs of prediabetes:
- All of the insulin resistance symptoms listed above
- Increased thirst
- Frequent urination
- Blurred vision
- Unexplained fatigue
- Slow-healing cuts or frequent infections
How Insulin Resistance and Prediabetes Are Treated
Fortunately, both insulin resistance and prediabetes can often be improved, or even reversed in some cases, with the right steps and treatments.
Lifestyle changes (first-line treatment for both):
- Nutrition: Focus on a balanced, whole-food diet rich in vegetables, lean proteins, healthy fats and moderate amounts of high-fiber, unprocessed carbs. When choosing carbohydrate foods, opt for those that retain their original food matrix, including fiber, micronutrients and phytochemicals, which all contribute to your health and slow your body’s glycemic response.
- Physical activity: Get at least 150 minutes of moderate exercise per week, such as walking, aerobics, cycling, dancing or swimming. Strength training can also help improve insulin sensitivity.
- Weight loss: Even losing 5-7 percent of body weight can cut diabetes risk significantly (sometimes in half), as obesity is a major risk factor.
- Sleep and stress management: Both conditions directly affect metabolic function, hormone balance and blood sugar levels. Aim for 7 to 9 hours of sleep every night and find ways to manage stress on a daily basis, such as spending time outdoors, reading, journaling or doing mindfulness practices.
Medications (more common for prediabetes or high-risk patients):
- Metformin may be prescribed if lifestyle changes alone aren’t enough.
- Newer medications, like GLP-1 receptor agonists, can also be considered in certain cases.
Prevention: Protecting Your Health Early
Since insulin resistance is the starting point for many metabolic problems, prevention matters. Screening is especially important if you have risk factors such as obesity, PCOS or a family history of diabetes.
Prevention tips:
- Maintain a healthy weight
- Eat more whole foods and fewer refined carbs and sugars
- Stay physically active daily
- Get enough sleep
- Limit alcohol and quit smoking
- Keep up with routine health screenings and doctor’s visits
When to See a Doctor
It’s important to schedule a visit with your healthcare provider if you:
- Have risk factors like obesity, high blood pressure or a family history of diabetes
- Notice early warning signs of either insulin resistance or prediabetes, such as constant fatigue, increased thirst and urination, new cravings or skin issues, or unexplained weight gain
- Haven’t had your blood sugar checked in the past 3 years (or sooner if you’re high risk)
Early detection allows for earlier intervention, which can prevent progression to type 2 diabetes and lower your risk of serious complications.
Stony Brook’s multidisciplinary team of Endocrinology, Diabetes and Metabolism experts provide comprehensive care for conditions like insulin resistance, prediabetes and type 2 diabetes. With advanced diagnostic tools, evidence-based treatment plans and a focus on lifestyle support, we help patients take proactive steps to protect their long-term health. If you need guidance on prevention, management or advanced treatment options, our endocrinology specialists are here to partner with you every step of the way. Find a provider here or call to make an appointment: (631) 444-0580.
